<h3>描述</h3>
<p>Select组件提供beforeSearch事件接口，监听搜索框的内容变更，可以获取到搜索框的内容</p>
<p>beforeSearch事件接口</p>
<h3>示例</h3>
<p>示例中，列表初始化时加载三条数据，搜索时加载全部的匹配的数据，比如在示例1搜索“国”，或者在示例2搜索“国”</p>
<h4>1.单选 + 后台搜索:</h4>
<br />
<button type="button" (click)="changeOptions()">改变下拉数据options(后台搜索时options支持动态变更)</button><br /><br />
<span>国家: </span>
<ti-select
  style="width: 120px"
  [searchable]="true"
  [options]="myOptions"
  [(ngModel)]="mySelecteds"
  (beforeSearch)="onBeforeSearch($event)"
  placeholder="请选择国家"
  id="myselect"
>
</ti-select>
<br />
<p>选中项：{{mySelecteds | json}}</p>
<br />

<h4>2.多选 + 全选 + 后台搜索，下拉选项中有禁用的:</h4>
<br />
<button type="button" (click)="changeOptions1()">改变下拉数据options(10.1.16 后台搜索时options支持动态变更)</button><br /><br />
<span>国家: </span>
<ti-select
  [multiple]="true"
  [selectAll]="true"
  [searchable]="true"
  [options]="myOptions1"
  [(ngModel)]="mySelecteds1"
  (beforeSearch)="onBeforeSearch1($event)"
  placeholder="请选择国家"
  id="myselect1"
>
</ti-select>
<br />
<p>选中项：{{mySelecteds1 | json}}</p>
<br />
